Geothermal Energy and Geothermal Power Plants | Lesson 7.1| Earth Science

Summary

This video lesson covers geothermal energy and its significance in the Philippines, where it is a leading source of renewable energy. It explains the basics of geothermal energy, how it is generated from heat within the Earth's subsurface, and highlights the geothermal gradient, which shows how temperature increases with depth. The video also describes the three main types of geothermal power plants: binary cycle, dry steam, and flash steam, detailing their processes and how they generate electricity. Lastly, it discusses the re-injection of water to preserve geothermal reservoirs.

Takeaways

• 🌍 Geothermal energy is a major renewable energy source in the Philippines, making up almost 45% of the country's renewable energy production.
• 🔥 Geothermal energy is the heat derived from the decay of radioactive elements like potassium, uranium, and thorium, as well as residual heat from Earth's formation.
• 🌡️ Aquifers are rock reservoirs containing groundwater, but not all aquifers are capable of producing geothermal energy.
• 💧 For an aquifer to be classified as a geothermal reservoir, it must have a heat source, like a hot rock or magma chamber.
• 📉 The geothermal gradient refers to the increase in temperature as you go deeper into the Earth's surface, typically around 3°C per 100 meters.
• 🔁 There are three types of geothermal power plants: binary cycle, dry steam, and flash steam.
• ⚡ In a binary cycle power plant, heat is transferred from geothermal water to a secondary liquid with a low boiling point, which drives a turbine to generate power.
• 💨 A dry steam power plant directly uses steam from a geothermal reservoir to rotate a turbine and generate electricity.
• 💥 A flash steam power plant uses hot water from a geothermal reservoir, which flashes into steam in a cold tank, turning a turbine to generate power.
• ♻️ In all geothermal power plants, the water or steam used is re-injected back into the geothermal reservoir to maintain sustainability.

Q & A

What is geothermal energy?

Geothermal energy is the heat that comes from the decay of radioactive elements like potassium, uranium, and thorium, as well as residual heat from Earth's formation. It involves techniques to recover heat from Earth's subsurface, particularly from aquifers containing groundwater.

How significant is geothermal energy in the Philippines?

Geothermal energy is a major renewable energy source in the Philippines, accounting for almost 45% of the country’s renewable energy. The Philippines is the second-largest producer of geothermal energy in the world.

What is an aquifer, and how is it related to geothermal energy?

An aquifer is a rock reservoir that contains groundwater. Not all aquifers can produce geothermal energy, but those connected with a heat source, such as heated rocks or magma chambers, are capable of generating geothermal energy.

What is a geothermal gradient?

A geothermal gradient is the rate at which temperature increases as you go deeper into the Earth. The average geothermal gradient is around 3°C for every 100 meters of depth.

What are the three types of geothermal power plants?

The three types of geothermal power plants are binary cycle, dry steam, and flash steam power plants.

How does a binary cycle geothermal power plant work?

In a binary cycle power plant, water from the geothermal reservoir is pumped into a chamber where it transfers heat to another liquid with a lower boiling point. This second liquid vaporizes, turning a turbine to generate electricity. The water is then re-injected into the reservoir to maintain the supply.

How does a dry steam geothermal power plant operate?

A dry steam power plant directly captures steam from a geothermal reservoir, which turns a turbine to generate electricity. The steam condenses into water, which is then re-injected into the geothermal reservoir.

How does a flash steam geothermal power plant function?

In a flash steam power plant, hot water from the geothermal reservoir enters a tank where it rapidly vaporizes into steam. This steam turns a turbine to generate electricity. After cooling and condensing, the water is re-inserted into the reservoir.

What role do radioactive elements play in geothermal energy?

Radioactive elements like potassium, uranium, and thorium decay over time, producing heat. This heat contributes to geothermal energy by heating rocks and aquifers deep within the Earth.

Why is it important to re-inject water into geothermal reservoirs?

Re-injecting water into geothermal reservoirs is essential to prevent depletion of groundwater and to ensure the sustainability of the geothermal energy production process.